Topographic influences on vegetation mosaics and tree diversity in the Chihuahuan Desert Borderlands

Poulos, Helen M.; Camp, Ann E.

doi:10.1890/08-1808.1

Cited by 54 publications

(44 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Piñon-juniper woodland is the dominant forest type which is comprised of Mexican piñon pine ( Pinus cembroides Zuccarini), alligator juniper ( Juniperus deppeana vonSteudal), gray oak ( Quercus grisea Liebmann), Graves oak ( Quercus gravesii Sudworth), Emory oak ( Q. emoryi Leibmann), and weeping juniper ( J. flaccida vonSchlechtendal) (Poulos & Camp, 2010). Lower elevations also contain small populations of one seed juniper ( J. monosperma Englemann) and red berry juniper ( J. pinchotii Sudworth) and oak shrublands that are dominated by Q. pungens Leibmann.…”

Section: Methodsmentioning

confidence: 99%

Tree mortality from a short-duration freezing event and global-change-type drought in a Southwestern piñon-juniper woodland, USA

Poulos

2014

PeerJ

Self Cite

View full text Add to dashboard Cite

This study documents tree mortality in Big Bend National Park in Texas in response to the most acute one-year drought on record, which occurred following a five-day winter freeze. I estimated changes in forest stand structure and species composition due to freezing and drought in the Chisos Mountains of Big Bend National Park using permanent monitoring plot data. The drought killed over half (63%) of the sampled trees over the entire elevation gradient. Significant mortality occurred in trees up to 20 cm diameter (P < 0.05). Pinus cembroides Zucc. experienced the highest seedling and tree mortality (P < 0.0001) (55% of piñon pines died), and over five times as many standing dead pines were observed in 2012 than in 2009. Juniperus deppeana vonSteudal and Quercus emoryi Leibmann also experienced significant declines in tree density (P < 0.02) (30.9% and 20.7%, respectively). Subsequent droughts under climate change will likely cause even greater damage to trees that survived this record drought, especially if such events follow freezes. The results from this study highlight the vulnerability of trees in the Southwest to climatic change and that future shifts in forest structure can have large-scale community consequences.

show abstract

Section: Methodsmentioning

confidence: 99%

Tree mortality from a short-duration freezing event and global-change-type drought in a Southwestern piñon-juniper woodland, USA

Poulos

2014

PeerJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…and an increase in topographic complexity would be expected to support a greater diversity of vegetation types (Radford et al 2005;Poulos and Camp 2010). Although intuitive, our finding is in contrast with those recent studies that have found the extent of habitat a stronger driver of woodland bird species richness as compared with environmental-(e.g.…”

Section: Landscape Heterogeneity Versus Extent Of Preferred Habitatcontrasting

confidence: 98%

“…This increased topographic complexity would be expected to support a greater diversity of microclimates, soil and vegetation types, which in turn provide a greater range of resources to be exploited Pineda and Halffter 2004;Radford et al 2005;Poulos and Camp 2010;Bishop et al 2014). Environmental heterogeneity associated with range in elevation has been shown to support greater diversity within numerous taxa, including frogs in Mexico (Pineda and Halffter 2004), and ants in South Africa (Bishop et al 2014).…”

Section: Different Responses At Different Scalesmentioning

confidence: 99%

Drivers of diversity at the local- and landscape-scale in a fire-prone landscape

Burgess¹

View full text Add to dashboard Cite

Determining the factors that generate and maintain patterns of biodiversity is a challenge central to ecology. To effectively manage heterogeneous landscapes for biodiversity conservation there is a need to understand the mechanisms driving the relationship between spatial heterogeneity and species richness at multiple scales. Disturbances such as fire affect landscape heterogeneity and are important influences on the distribution and abundance of biota across a range of scales. A key challenge for biodiversity conservation in fire-prone ecosystems is thus to understand the influence of fire on biotic communities.Contemporary ecological fire management resounds with the term 'pyrodiversity'. Efforts to achieve pyrodiversity are usually motivated by the rationale that increasing gamma diversity relies upon maintaining a mosaic of patches of different fire histories. From a global review of literature, this thesis revealed that despite widespread acceptance of this paradigm, the evidence supporting it is extremely sparse. This dearth of knowledge of how heterogeneity affects biota limits effective application of the mosaic burning approach. Studies that consider the spatial and temporal attributes of the fire regime mosaic, and investigate the relationship between these and multiple taxa at different spatial scales, are urgently required.To respond to this knowledge gap, this thesis investigated the effects of fire history and habitat heterogeneity on structure and composition of floral and avifaunal communities. This thesis tests hypotheses about the importance of variable fire regimes, spatial heterogeneity, extent of habitat, and local-and landscape-responses on birds and their habitat in the fire-prone sub-tropical woodlands of central Queensland. Two methods were used to collect the data: i) digital mapping and characterisation of the fire regime mosaic; and ii) surveys of woody vegetation and avifaunal communities.The post-fire response of vegetation reflects not only a single fire event but is the result of cumulative effects of previous fires in the landscape. Fire history categories based on unique combinations of time since last burn, fire frequency and season of last burn were developed and used to map the fire regime mosaic of the study area. This thesis establishes that fire history category strongly influences richness and abundance of mid-storey trees and of individual plants currently comprising the mid-level strata. The particular elements of fire history, time since fire and fire frequency, had the strongest influence on vegetation structure. A longer time since fire (> 4 years since last burn) combined with infrequent fires (< 2 fires in 12 year period) appeared to iii promote a dense mid-storey with the opposite conditions promoting more-open woodlands. This is of particular relevance for conservation management of woodland birds that have been shown to respond strongly to habitat structural variables in the study area.Landscape heterogeneity and extent of habitat are each expected to c...

show abstract

“…Neste sentido, a abundância e a distribuição espacial das espécies nas comunidades vegetais podem ser reflexos das necessidades do seu nicho ecológi-co, além de reflexos das variações ambientais no tempo e espaço (Poulos & Camp 2010). Por outro lado, contrário às expectativas oriundas da teoria baseada em nicho, a teoria neutra prediz que a limitação de dispersão, especiação e o papel da estocasticidade ao longo do tempo podem levar espécies ecologicamente equivalentes a formarem padrões de distribuição e abundância similares àqueles observados na natureza (Hubbell 2001).…”

Section: Introductionunclassified

Padrões espaciais e ecológicos de espécies arbóreas refletem a estrutura em mosaicos de uma floresta subtropical

et al. 2012

View full text Add to dashboard Cite

RESUMO(Padrões espaciais e ecológicos de espécies arbóreas refletem a estrutura em mosaicos de uma floresta subtropical). A abundância e distribuição espacial das espécies podem ser reflexos das necessidades do seu nicho ecológico, além de reflexos das variações ambientais no tempo e espaço. Os objetivos do presente trabalho foram analisar a distribuição espacial e grupos ecológicos das espécies arbóreas em um remanescente de floresta subtropical e avaliar a interferência destes padrões sobre métricas de riqueza e diversidade. Os padrões espaciais foram avaliados considerando uma área amostral de 1 ha dividida em unidades amostrais contíguas de 10 x 10 m, onde todos os indivíduos com perímetro à altura do peito ≥ 15 cm foram amostrados. A descrição dos padrões foi obtida por meio de correlogramas (índice I de Moran), considerando diversas classes de distância, índices de agregação e diagramas de superfície. A co-ocorrência entre espécies foi analisada por meio de índices de associação espacial. A maioria das espécies apresentou distribuição agrupada e com autocorrelação espacial positiva, sobretudo para as menores classes de distância, indicando a formação de pequenos grupos de indivíduos. Da mesma forma, 17 espécies apresentaram associações espaciais (co--ocorrências), formando densos agrupamentos e, embora não tenham interferido sobre a riqueza específica, Casearia sylvestris e Ocotea diospyrifolia diminuíram a equabilidade em alguns setores da área. Espécies tolerantes à sombra apresentaram-se associadas, bem como, espécies dependentes de luz, indicando que a dinâmica de mosaicos pode interferir diretamente sobre a distribuição das espécies, sobretudo pela limitação de dispersão.Palavras-chave: autocorrelação espacial, correlogramas, índices de distância, limitação de dispersão, riqueza de espécies ABSTRACT (Spatial and ecological patterns of tree species reflect patch dynamics of a subtropical forest). The abundance and spatial distribution of species may reflect on niche requirements, interactions among individuals and across as time and space. In this way, the aims of this work were to analyze tree species distribution and ecological groups in a remnant of subtropical forest to evaluate the interference of such patterns over richness and diversity metrics. We evaluated the spatial patterns of a 1 ha area divided into 10 x 10 m sampling units where we surveyed all living trees with perimeter at breast height ≥ 15 cm. Pattern descriptions were obtained by using correlograms (Moran's I) over several distance classes, aggregation indices and surface diagrams. The co-occurrence among species was obtained by using spatial association indices. Furthermore, 17 species showed aggregated distribution and positive spatial autocorrelation, mainly in the shorter distance classes, which indicated the occurrence of several small groups of individuals. In addition, many species were spatially associated with dense groups and although such groups do not influence species richness, Casearia sylvestris and Ocotea diospyrifol...

show abstract

Topographic influences on vegetation mosaics and tree diversity in the Chihuahuan Desert Borderlands

Cited by 54 publications

References 55 publications

Tree mortality from a short-duration freezing event and global-change-type drought in a Southwestern piñon-juniper woodland, USA

Tree mortality from a short-duration freezing event and global-change-type drought in a Southwestern piñon-juniper woodland, USA

Drivers of diversity at the local- and landscape-scale in a fire-prone landscape

Padrões espaciais e ecológicos de espécies arbóreas refletem a estrutura em mosaicos de uma floresta subtropical

Contact Info

Product

Resources

About